The field of the invention pertains to the manufacture and configuration of bottles, in particular, thin walled plastic bottles.
Bottles manufactured of flexible plastics with thin wall thickness generally rely upon the curvature of the bottle shape to provide the necessary rigidity to the bottle. A flat sided bottle, however, must rely upon the inherent rigidity of the plastic material and sufficient wall thickness to prevent excessive bowing out distortion of the flat sides when the bottle is filled to capacity.
In a currently pending U.S. design patent application by the inventor, Ser. No. 06/903,102, a circular central depression in each major side of the bottle is bonded together at the bottle center and a depressed midriff rib circumferentially extends about the bottle at the circular depression. This configuration has been found to stiffen the major flat sides of the bottle, in particular, water bottles of two to four gallon capacity. The solid circular bonded depressions of this design without a hole there through have been found superior in rigidity to a bottle with a circular hole there through.
However, improvements to further stiffen by configuration and thereby allow a decrease in wall thickness and bottle weight are a desirable goal.